OPB, Oregonian and Portland City Club say Linfield research changes debate about bike trails in Portland’s Forest Park

Published May 20, 2010

Nancy Broshot has recorded tree health in Portland’s Forest Park for 17 years, and her findings are especially relevant now.

The city of Portland is drafting final recommendations for how cyclists use one of the country’s largest urban parks, and that discussion, regional news outlets say, should be informed by Broshot’s scientific study.

The issue of public use turned controversial after a rogue mountain bike trail was cut through the forest in February, but even greater threats endanger one of the country’s largest urban parks, according to the Linfield environmental studies professor.

Broshot’s data shows that few saplings are coming up or surviving, and the mortality rate of all but the oldest trees has increased dramatically. Even in the more remote section of the park, significant numbers of trees have died. She also found that the density of young trees has declined by half.

“In other Western states high tree mortality has been linked to water stress, and ultimately, to global warming,” Broshot said. “Decline may also be attributed to natural successional processes, human disturbance or pollution.”

“We know the park’s trees are in trouble,” she said. “Now we need to look at why.” She plans further study at 24 sites in the park.

Oregon Public Broadcasting, The Oregonian, a Portland City Club report, KGW Channel 8 News, the Portland Tribune, Willamette Week and other news outlets covered Broshot’s research.